[Amps] Plate Impedance, ARRL

R at contesting.com R at contesting.com
Thu Apr 27 06:44:54 EDT 2006

On Apr 26, 2006, at 9:56 AM, Jim Kearman wrote:

> From: "Will Matney" <craxd1 at verizon.net>
>> I'm not knocking using 1.8 as that's what I use and it works. The 
>> reason I
>> broought all this up is that they do not make it clear from what I 
>> read that
>> these factors are for triodes only that I seen.
> I suspect that when that section was written, the League was 
> publishing only triode amplifiers. For many years until George 
> Daughters published his 4CX1600B amplifier, all Handbook amps used 
> triodes.
> I got the insight into the differences from reading Rich Measures's 
> site. It's interesting to read the history of his Handbook chapter, 
> which was presumably rejected mainly for political reasons.

It was a bit more than just that.  The principal force in Newington is 
seemingly not the vote of members, like Washington, D. C., it's the 
influence of greenbacks, and two amplifier manufacturers who advertised 
heavily in QST were definitely not happy with my article "The Nearly 
Perfect Amplifier" (January, 1994).
   Another factor was the ARRL's Official Observer Program.  During the 
early 1980s, there were a number of Official Observers here in the Land 
of the Fruits and Nuts who were running amuck sending out OO cards 
that, for lack of a better word, were just plain stupid.  As a result, 
I came up with the Official Observer Observer card so that people who 
received OO cards that were inane could reply in same.  When the two 
guys at Newington who handled the articles I wrote got wind of the OOO 
card, I sent them a sample pack.  Both posted an OOO card above their 
desk and reportedly got some chortles from other Staff members.  One of 
those who most definitely did not laugh was the OO Program Manager, 
Dick Palm.  When he eventually figured out who the dastardly author of 
the OOO card was, he brought it up at the next general meeting and, 
according to an attendee who later telephoned me, I got blacklisted for 
heresy.  Subsequently, the Handbook Editor, Bob Schetgen, telephoned 
me, broke the contract I signed with the ARRL, told me to stop writing 
the amplifier chapter for the Handbook and informed me that Tom 
(MFJ-Ameritron) and Dick (Alpha) had replaced me.  And that's when I 
decided to make the manuscript available for free on the Internet.

> As load impedance calculations are based on the plate-voltage swing, 
> it seems intuitive that the k factors for triodes and 
> tetrodes/pentodes would be different.
>> Also, the terms differences that
>> we use where they say the plate load resistance is the same as plate 
>> impedance.
> Assuming the load is matched, the plate is looking into a non-reactive 
> impedance, so the terms could be interchanged. Considering the load as 
> an impedance, though, is more in line with the fact that we are 
> dealing with ac and reactances, not dc and pure resistors. My guess is 
> the confusion stems mostly from erratic editing of the Handbook. 
> Certain chapters are chosen for revision and updating each year. Other 
> chapters, even though they may contain known errors, are not touched.

The great continental divide was the departure of QST Technical Editor, 
George Grammer, W1DF, a man who understood two things:  the laws of 
electricity, and that QST's success depended on it's credibility.  
Basically, Grammer made equipment manufacturers an offer they could not 
refuse -- i. e., fix design problems or QST will review them in the 
Product Review.

> It might pay to take several years' worth of Handbooks, cut them up, 
> and reassemble them to produce one relatively error-free copy!
> 73,
> Jim, KR1S
> http://kr1s.kearman.com/
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> Amps at contesting.com
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Rich Measures, 805.386.3734, AG6K, www.somis.org

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